In general, a high voltage battery is used in a hybrid vehicle or an electric vehicle as a part or all of a power source. In order to protect the high voltage battery, a high voltage relay needs to be used.
The high voltage battery is mounted on a vehicle in a form of one pack by serially connecting about 50 to 100 cells according to a necessary capacity of the battery. The high voltage battery pack has excellent energy density and efficiency, but when the high voltage battery pack is overcharged, there is a risk in that the high voltage battery pack is inflated or exposed, so that a battery management system (BMS) controls a high voltage relay.
That is, when the BMS monitors a sum of the voltages of the entire cells or the voltage of the battery pack, and the sum of the voltages of the entire cells or the voltage of the battery pack is equal to or larger than a reference voltage, the BMS compulsorily opens the relay to prevent the battery from being charged any more, or outputs zero as an available voltage so as to prevent another system from being damaged.
However, since the BMS controls the relay only with a control signal through a microchip therein, when the BMS has a problem due to a vehicle accident, or an erroneous operation of a BMS electronic system is performed, the relay is not properly controlled, so that there is still a risk that the battery may catch on fire or explode.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.